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Two trends in geographic information science today are affecting Environmental Information Systems (EIS): standardization in Geographic Information Systems (GIS), and the application of middleware technology in heterogeneous computing environments. Research problems arise when the two trends meet each other in the EIS domain. In GIS, standardization is important for geospatial data sharing and geospatial service interoperation. The OpenGIS Consortium (OGC) published abstract specifications and partial implementation specifications, which can make diverse geospatial data and geospatial services accessible to conforming applications. For example, the OGC Simple Feature (SF) and Grid/Coverage (GC) geospatial data specifications specify the format and operations on geospatial feature (vector data) and coverage (raster data) as OpenGIS Simple Feature and Grid Coverage; the OGC Web Feature Server (WFS), Web Coverage Server (WCS), and Web Map Server (WMS) can publish and manage geospatial features, coverages, and maps via the Web. However the implementation specifications are still incomplete. With increasing applications of middleware technology, such as Common Object Request Broker Architecture (CORBA), Distributed Component Object Model (DCOM), and Java Remote Method Invocation (RMI), in GIS and EIS, it is necessary to design feature, coverage, and map server implementation specifications for CORBA, DCOM, and Java RMI. This paper presents an integrated feature-coverage-map server implementation specification for CORBA; similar to the OGC WFS, WCS, and WMS implementation specifications, it provides the access to features, coverages, and maps in a CORBA environment. Clients conforming to the implementation specification can interact with a CORBA feature-coverage-map server using the OpenGIS Simple Feature and Grid Coverage. An implementation based on the specification is also presented. The implementation transformed GRASS, an open source GIS, into a CORBA feature-coverage-map server. The evaluation results show that OpenGIS-based interoperability comes at an acceptable cost in terms of performance. The primary contributions of the paper are first that it presents an OpenGIS conforming feature-coverage-map server implementation specification for CORBA, and second that it presents a demonstration implementation and evaluates its performance.
Keywords: CORBA, Coverage Server, EIS, Feature Server, GIS, GRASS, Map Server, OpenGIS